Tank bodies and pipe have been made of glass fiber reinforced thermosetting resin by both continuous and non-continuous processes. In a continuous process, resin and glass fibers are applied to a rotating and advancing cylindrical surface formed by a continuously recirculating helically wound steel band. In a non-continuous process, resin and glass fibers are applied to an elongated longitudinally slit collapsible tubular shell rotatable about a horizontal axis and supported from only one end, leaving the other end free for withdrawal of the product after the resin is cured. For different sizes of pipe interchangeable slit tubular shells of different diameters have been used with the same driving and support mechanism, each tubular shell having its own extensive inner supporting framework and set of actuators for collapsing thereof.